TNF-alpha stimulation increases dental pulp stem cell migration in vitro through integrin alpha-6 subunit upregulation

- Tumor necrosis factor-α (TNF-a) plays a role in migration of human dental pulp stem cells.
- TNF-α at a concentration of 50 ng/ml enhances hDPSC migration in vitro.
- Intgerin α6 expression plays a role in chemotactic migration of TNF-α treated cells.
- SiRNA treatment for reducing integrin α6 expression in hDPSCs causes a decrease in their migration potential and the cells lose their sense of directionality.
- Cytoskeletal changes in TNF-α treated group of cells are in line with the migratory phenotype in hDPSCs.

ObjectiveThe dissemination of stem cells into tissues requiring inflammatory and reparative response is fundamentally dependent upon their chemotactic migration. Expression of TNF-α is up regulated in inflamed pulps. Dental pulp cells are also known to express integrin α6 subunit. Expression of integrin subunit α6 has been linked to the acquisition of migratory potential in a wide variety of cell types in both pathological and physiological capacities. Therefore, in this study we examined the effects of a pleiotropic cytokine TNF-α on the migration of hDPSCs and investigated its relationship with expression of integrin α6 in hDPSCs during chemotactic migration.DesignhDPSC cultures were established. Protein expression profile of α6 integrin subunit was determined. Effect of exogenous TNF-α (50 ng/ mL) on hDPSCs' migration potential was evaluated by transwell inserts and in vitro scratch assay. Upregulation/downregulation of TNF-α mediated migration was assayed in presence/absence of integrin α6 respectively. To suppress integrin α6 expression, cells were transfected with integrin α6 siRNA and then cell migration and cytoskeletal changes were evaluated.ResultsOur results showed significant increase of hDPSCs' migration after stimulation with TNF-α. By knockdown of integrin α6, which is upregulated by TNF-α, we observed a decrease in the TNF-α directed chemotaxis of hDPSCs.ConclusionIn this study, we show that activation of integrin α6 brought about by TNF-α led to an increase in migratory activity in DPSCs in vitro thus describing a novel association between a cytokine TNF-α and α6 chain of an adhesion receptor integrin in regulating migration of hDPSCs.